Earnings Per Share (Narrative) (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Income (Loss) from Continuing Operations, Per Basic Share	$ (0.30)	$ 0.26	$ (0.16)	$ 0.20	$ (0.11)	$ 0.26	$ 0.11	$ 0.21	$ 0.00	$ 0.48	$ 0.98
Income Loss From Continuing Operations Diluted										$ 331	$ 705
Antidilutive securities excluded from computation of earnings per share									8	8	6
Earnings Per Share, Basic	$ (1.44)	$ 0.26	$ (0.73)	$ 0.19	$ (0.13)	$ 0.27	$ 0.10	$ 0.20	$ (1.72)	$ 0.45	$ 1.07
Convertible Debt Securities [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share									15	15	15